Bidirectional stepping motor servosystem



Feb. 14, 1961 R. J. SILHAVY 2,972,093

BIDIRECTIONAL STEPPING MOTOR SERVOSYSTEM Filed Oct. 10, 1958 470 rweg,

United States Patent BIDIRECTIONAL STEPPING MOTOR SERVOSYSTEM Raymond J.Silhavy, Chicago, 111., assignor to Oak Manufacturing Co., a corporationof Delaware Filed Oct. 10, 1958, Ser. No. 766,482 2 Claims. (Cl. 318-19)This invention relates to a bi-directional switch homing system and moreparticularly to a system utilizing a multi-position master switch forcontrolling one or more multi-position slave switch sections.

Master controlled switch systems have wide uses in many fields. As anexample, such systems may be used in connection with building elevatorsand in the remote control of various kinds of apparatus and devices.

Rotary switch systems wherein the position of a slave switch unit iscontrolled by the position of a master switch unit are well known. Insuch systems, a master switch unit may be turned by any suitable meansto any one of a number of predetermined positions and this will causethe slave systems to follow and move a slave switch section to acorresponding similar position. In such systems, it may be necessary tomove the master switch section in a predetermined direction. In suchinstance a master switch section may be turned from one predeterminedposition to another through the smallest angle but the slave sectionscan only travel in a definite direction and will take the longest wayaround to get to the predetermined position. As a result of suchoperation, the speed of operation of such a switch system is reduced andresults in increased wear on the various components of the systembecause of the greatly increased operation and travel. A

A system embodying the present invention has great flexibility inpermitting a master switch section to be turned in one or other desireddirection with the assurance that the slave switch sections will reachthe desired position by the shortest amount of travel. It is clear thatif rotary motion is involved, there will be two directions that a slavesection can take in going from one position to another position.However, one direction will always involve a smaller range of travelthan the other direction.

A system embodying the present invention provides that the slavesections will always take the direction of travel which will provide thequickest and shortest travel between two points.

In order that the invention may be understood, reference will now bemade to the drawing wherein the single figure illustrates indiagrammatic form a system embodying the present invention. The variousswitch sections are shown from one side only so that the rear of aswitch section will appear as though transparent.

In the operation of the new system, rotary switch sections are used.While many different rotary switch constructions may be used, a switchconstruction which is convenient and useful is disclosed in UnitedStates Patent No. 2,186,949 issued on January 16, 1940.

Also forming a part of the new system is a. solenoid mechanism forstepping the rotary switch along one switch position at a time. Whilemany such stepping means are known and may be used, a rotary solenoidiwhichmay be used with rotary switch sections is disclosed in UnitedStates Patent No. 2,812,453 issued November 5, 1957.

Referring specifically to the drawing, there is illustrated masterswitch section A having a rotor section A1 which may be turned by anysuitable means, here symbolically illustrated as knob A2 coupled to therotor. Switch section A is here illustrated as having 24 positionsalthough this number may be varied to suit requirements. Accordingly,the stator of section A is provided with 24 fixed contacts numberedrespectively 1 to 24 inclusive.

Rotor Al has a single tongue as illustrated in the drawing functioningas an active rotary contact which is adapted to cooperate successivelywith each of the 24 stator contacts. Rotor A1 is connected by wire A4which functions as a common return from switch section A. Wire A4 isconnected to one terminal, here illustrated as the positive terminal ofa source of direct current. The connection of rotor A1 may be effectedin any one of a number of ways. For example, the reverse side of sectionA may contain a grounding ring electrically joined to the rotor contactand cooperating with a stator contact. Other means for effecting aground or common connection to the rotor contact of rotor A1 may beprovided.

Cooperating with master switch section A are slave switch sections B-Band C-C respectively. Each of the slave switch sections has two sideswhich, for convenience, are referred to as B and B and C and C,respectively. As is clearly indicated in the Patent 2,186,949 previouslyreferred to, the stator and rotor of the switch section can haveelectrical contacts on opposite sides thereof.

The slave switch section must correspond to the master switch section inregard to the numbere of switch positions. Thus, switch sections B-B'and C-C have 24 positions. Referring to switch section B-B', both faceshave stator contacts numbered 1 to 12 inclusive arranged as illustrated.Thus, on both faces of slave section BB', stator contacts 1 to 12 areconsecutive and in a 24 position switch would subtend an angle of a bitless than Actually a 24 position switch has the 360 subdivided into 25parts with the angular separation between the center lines of adjacentcontacts being about 14.4".

Since B shows the rear face of the switch section as seen from thefront, it is evident that stator contacts 1 to 12 of B will be oppositecorresponding contacts 1 to 12 of face B. In other words, slave switchsection B-B' will have 24 contacts distributed on the stator to coverpositions 1 to 12 inclusive and the opposite pairs, such as number 1 or2 or 3 will be electrically connected together. The same numbers areused for the stator contacts to show switch position and electricalconnections. Thus all No. 1 contacts will be connected together. All No.2 contacts will be connected together and so on.

The rotors for slave section BB' have rotor contacts B1 and B'l onopposite faces thereof. These two rotor contacts are electricallyseparate from each other. Rotor contact Bl has an active contactextension as illustrated for engaging the stator contacts, saidextension having an angular extent of 11 switch positions, this beingone less than half of the 24 position range. Rotor contact 8' on therear face has its active contact engaging part angularly offset 180 fromthe effective contact portion of B1 and subtends 12 switch positions,one half of the entire range.

Slave switch section C-C is generally similar to slave section B--B.There are two differences. The stator contacts for slave section C-C'are numbered 13 to 24 inclusive and the rotors are reversed.

The rotor contacts on slave sections C-C are identical with B--B'insofar as construction is concerned. But in CC, rotor contact C1subtends 12 switch positions whereas rotor contact Cl subtends only 11switch 7 positions. All contacts 1-3 to 24 inclusive are electricallyinterconnected.

Each of the rotor contacts of the slave sections are provided with aground stator contact as shown which engages the rotor contact at alltimes. Ground stator contacts B and B5 are cross-connected to groundstator contacts C5 and (3'5. Thus, ground contact B5 is directlyconnected by wire to ground contact CS. Ground contact C5 is directlyconnected by wire to ground contact B5.

The two switch slave sections B-B' and C-C' are coupled to a commonshaft and the shaft is mechanically coupled to two rotary solenoids ofany desired construction, such as, for example, disclosed in the patentpre viously identified. The solenoid BS is adapted to cooperateelectrically with slave section B-B' while solenoid CS is adapted tocooperate with slave section CC. This cooperation determines thedirection in which the shaft is turned. In the case of BS, the rotationof the solenoid would be clockwise as seen from the front of the switchsection's. Solenoid CS would turn the switch sections in the reversedirection.

As disclosed in the patent, the operating winding of each of thesolenoids is electrically coupled through a switch section for cuttingoff the solenoid current as or just before the switch section reachesthe end of its travel 'for one operating cycle to permit the solenoid toreturn to starting position It is understood that an operating cycle fora solenoid results in the switch section being turned through one switchposition.

Each switch control is symbolically illustrated in connection with slavesections BB and CC"by a cam adapted to cooperate with a spring switchcontact for momentarily opening the circuit of an operating winding.Inasmuch as this switch control action of the solenoid is fullydisclosed in the patent referred to above, a detailed descriptionthereof will not be given here.

Solenoids BS and CS have one terminal on each of their respectiveoperating windings connected to what is here illustrated as the negativeterminal of the direct current power source. The other terminal of eachof the solenoid windings is connected through therespective controlswitch on the correspondingswitch section to the grounding contact forthe rotor of the front face of each slave section.

to the master section position.

One desirable feature of the invention resides in the fact that if thepower happens to be cut off from the system, movement of any one of theswitch sections will not have any serious effects. In other words, ifthe power source happens to be dead, and'if master switch section A ismoved, it is clear that the slave sections will not operate because oflack of power. However, as soon as the power comes on,the slave switchsections will immediately assume a position corresponding to the masterswit-c section.

In order that the operation may be clearly understood,

'let it be assumed that master section A is turned so that rotor A1makes contact with stator contact No. 6 of A. A circuit will beestablished from the positive terminal of the power supply through wireA4 and the rotor contact of A to stator contact 6 of A.

From stator contact 6, the circuit will continue to contacts6 of slavesection B-B'. Due' to the position of rotor Bl, contact 6 of B' willhave not efiect. However, contact 6 of the front face B of the switchsection contacts rotor B1. The circuit will continue through groundcontact B5 to cause BS to operate. BS will rotate the entire assembly ofslave sections clockwise as seen from the front until rotor Bl no longermakes contact with stator contact No. 6 of B. At this point rotorcontact Bll will close on contact 5 of B. Position 6 is dead on B1 andBl when solenoid BS stops at 6. However, this will be ineffective sinceBl goes to C5 and the circuit is open. This is because section CC has noconnections to any No. 6 contact. Also note that Cl and Cl rotorcontacts are not connected to each other.

It should be noted that it makes no difference in which direction mastersection A is turned to reach contact 6 of section A. It is true that ifmaster section A is turned relativeiy slowly, then the solenoids may befast enough so that the slave sections will be stepped in the samedirection as the master. However, if master section A is turned fromcontact 1 as shown to contact 6 in a counterclockwise direction (thelong way around) and if this is done fast, the action described due tosolenoid BS will occur.

The corresponding action will occur with solenoid CS if the masterstation A is turned to select any one of switch positions 13 to 24inclusive.

Due to the differences in angularity of the active portions of the rotorcontacts B1 and Bl; C1 and C1 and the reversal of the rotor arrangementsof sections B--B' and C-C, there will be no point to which the manualcontrol can be turned where the slave sections will be at dead center.in other words, the new system provides for discrete operating positionsnone of which will be exactly from any previous position. Hence, theslave sections will always have a longer and shorter path of travel fromone position to any other position and will automatically select suchshorter path. 7

Itis understood that the two rotary solenoids and slave sections willall be coupled to the same shaft although only one solenoid will ever beactive at any one time. It is evident that any number of slave systemsmay be provided, each slave system having its pair of rotary sole-.noids and complement of slave switch sections; Each complete slavesystem will be connected in parallel to the first slave system so thatin effect the master switch section I A will control each slave system.

The master switch section A can be replaced by a push button type ofswitch for selecting one switch positionat .a time. Y

What is claimed is:

g l. A bi-directional remote control master and slave system adapted tooperate over a predetermined number of separate index positions, saidsystem comprising a master switch section, such switch section having acommon return and having a number of separate switch contactscorresponding to a number of total operating switch positions, saidmaster switch including means for selecting a switch position so that acorresponding switch contact is connected to said common return, atleast one remote slave section, said slave section comprising fouroriented rotary switch sections, the first and second switch sectionsoperating as one unit for movement in one direction, the third andfourth switch sections operating as a second-unit for movement intheopposite direction, a common shaft for all said four switch sections,each switch section including a rotor rotatively coupled to said shaft,each switch section including a stator having a plu- .rality of activecontacts, each of the four switch sections having index switch positionsequal in number to the switch positions of said master switch section.the first two switch sections having active stator contactscorresponding to the first halfof the total index switch positions withcorresponding contacts for the same switch position connected together,the rotors for said first two switch sections each having rotor contact,each rotor contact having an active switching portion, the active rotorswitching portion of the first switch section subtending an angle equalto one less than one half the number of index switch positions, theactive rotor contact for the second switch section subtending an angleequal to one-half the number of index switch positions, the active rotorcontact portions of the first two switch sections being angularlydisplaced by one-half of the total number of index switch positions, thethird and fourth switch sections being correspondingly constructed, thethird and fourth switch sections having active stator contactscorresponding to the second half of the total index switch positions,the rotor contacts for the third and fourth switch sections beingsimilar to the rotor contacts for the first two switch sections exceptthat the third rotor contact is the one which has the active portionsubtending an angle equal to one-half of the index switch positions,wires connecting the active contacts corresponding to the same switchpositions of the master switch section and the switch sections, a grounding contact for each rotor contact of the four switch sections, crossconnections between the rotor grounding contact of the first and fourthswitch sections on the one 29 hand and between the second and thirdswitch sections on the other hand, stepping means including a windingfor stepping said four switch sections one switch position at a time inone direction, similar stepping means including a winding for steppingthe four switch sections in the reverse direction, a connection from oneterminal from said one stepping means winding to the grounding contactfor the rotor of the first switch section, a connection from the oneterminal of the other stepping means winding to the grounding contact ofthe rotor switch section, and a common connection at the remainingterminals of the windings of the two stepping means, said last namedcommon connection and the common return for the master switch sectionconstituting terminals for connection to a source of electric power forenergizing the stepping means. 7

2. The system according to claim 1 wherein said master switch section isof the rotary type, said common return therefor including a rotarymovable contact cooperating with the separate stator switch contacts.

No references cited.

